China’s major industrial firms ended their period of profit losses and reaped good returns in 2016 on the back of a construction boom, the National Bureau of Statistics (NBS) said Thursday.

Those companies reported an 8.5 percent profit increase in 2016, reversing the 2.3 percent decline registered in 2015, the NBS said in a statement.

NBS statistician He Ping said the profitability of the major business of industrial firms rose 0.19 percentage points year on year to 5.97 percent in 2016.

In December, their profits grew 2.3 percent year on year, slowing by 12.2 percentage points from November.

The sharp profit slowdown in December was a result of soaring raw material prices, which pushed up China’s producer prices to their highest level in more than five years.

Earnings recovery remained uneven across the sector, with coal mines and processors such as steel mills and oil refiners continuing to see smaller profit declines, while the advanced manufacturing sector saw its profits accelerate.

In 2016, profits of state-owned industrial enterprises rose 6.7 percent, while those of private companies increased 4.8 percent. Foreign-invested companies posted strong growth of 12.1 percent in profits.

He Ping partly attributed 2016’s brisk growth to a lower comparison basis in 2015. The average growth rate of profits in the past two years was less than the growth rate of industrial production, he added.

He underlined the fact that China’s economy faces a complicated domestic and global environment, and the foundation for industrial recovery is not solid.

Supply-side reform should be deepened, an industrial upgrading should continue, he added.

China’s economy grew 6.7 percent year on year in 2016, slowing from the 6.9-percent growth registered in 2015.

China’s economy continued to run within a reasonable range, with its structure further optimized and development model transformed, NBS chief Ning Jizhe said earlier this month.